Apparatus for lining wells



y 26, 1964 E. R. JENNINGS 3,134,442

APPARATUS FOR LINING WELLS Original Filed Oct. 27, 1958 EARL R. JENNINGS INVENTOR.

ATTORNEY United States Patent 3,134,442 APPARATUS F911 LINHJG WELLS Earl R. Jennings, Tulsa, Bhla, assignor to Pan American Petroleum Corporation, Tulsa, Skin, a corporation o1 Delaware Original application fict. 27, 1953, sex. No. 769,941 new Patent No. 3,028,915, dated Apr. 10, 1962. Divided and this application May 5, 1961, Ser. No. 117,257 3 Claims. (Cl. 166-297) This invention relates to producing a liner in a well. More particularly, this invention is directed to an improved well liner and a method and apparatus for placing it in a well and especially in a well casing to plug holes or perforations in the casing. This application is a division of my application S.N. 769,941, filed Oct. 27, 1958, now Patent No. 3,023,915, which is in turn a continuation-in-part of my application Serial Number 702,466, filed December 12, 1957, and now abandoned.

Liners have been placed in wells for many purposes including the recovery of circulation in a drilling well, shutting off the flow of undesirable fluids into a well, plugging casing leaks or perforations, and the like. A liner is typically shorter than the depth of the well and small enough to pass through the well and any casing therein. It is lowered to the proper elevation in the well where the liner is sealed at one or both ends to the well wall or to the casing already in the well. Such liners have generally been diflicult to install and seal in a well, have reduced the diameter of the well and accordingly the producing efficiency of the well, and have generally been too expensive to be widely acceptable in the art.

It is, therefore, an object of this invention to provide a liner for a well which will not materially decrease the diameter of the well, which can be set in the well with a minimum of expense, and which will make a fluid-tight seal with the well wall or with the casing therein. It is another object of this invention to provide an improved method and apparatus for setting such a liner in a well. Other objects of this invention will become apparent from the following description. In this description reference will be made to the accompanying drawings in which:

FIGURE 1 shows partially in vertical cross section, an apparatus suitable for setting my improved liner in a well;

FIGURE 2 is a cross-sectional View taken on the line 22 of FIGURE 1; and

FIGURE 3 is a cross-sectional view similar to FIG- URE 2 showing the improved liner and liner-setting apparatus in an expanded position in a conduit.

This invention may be described in brief as a fiber reinforced plastic well liner. It includes an improved procedure and apparatus for setting and curing a plastic liner in place in a well. An important element of this invention is an expandable setting tool for plac ng such liners in Wells.

Reference will now be made to the drawings for a more detailed description of the procedure for making up a fiber reinforced plastic well liner and an apparatus suitable for running and setting the liner. The liner setting tool includes primarily an expandable mandrel 18 which is made up at the surface and attached to the lower end of a tubing string 11. This mandrel includes a resilient expansion member such as a rubber tube 12. This tube may be expanded diametrically by compressing it axially but preferably the expandable element is expanded by inflating it with a gas or liquid under pressure. Longitudinal or spiral reinforcing cords may be molded in the tube to increase its strength. This tube may be of any length, typically between about one and 3,134,442 Patented May 26, 1 .964

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about 50 feet or more, depending upon the length of the liner which is to be placed in a well. The wall thickness of the tube may also be varied over a substantial range depending upon the diameter and particularly upon the pressure used to inflate the tube. A thickness of from about A inch to about one inch, typically about /2% inch for an inflation pressure of about 100460 pounds has been found satisfactory. The external diameter of the tube unstressed is desirably about 1-2 inches less than the diameter of the casing or the well in which the liner is to be placed or through which the liner is to be run so that the resindmpregnated fiber or fabric sleeve 13, which is built up around this tube and which eventually will become the liner, can be lowered easily through the well to the position at which the liner is to be set.

This elastic or expansible tube is connected to a tubular body 14 by upper and lower clamps l5 and to, respectively, which hermetically seal the tube to the body so that fluid pressure applied internally will expand or inflate the tube. The body has a central perforated section 17 threaded to the upper head 13 and to the lower head 19. This section has one or more fluid passages or perforations 21 which provide fluid communication between the inside of the tubular body and the inside of the tube 12 so that the tube may be inflated by the application of fluid pressure via the tubing string and the body. A fluid bypass conduit 22, connected as by welding, rolling, or the like at the upper end to upper head 18 and at the lower end to lower head 19, extends through the body and terminates outside the body above and below the ends of the tube 12 so that fluid pressure in the annular space outside the mandrel above and below the tube will be equalized at all times, particularly when the tube is expanded and while the resin in the liner is curing as hereinafter described. A knockout or shear plug 23 is threaded into the body 14 above the by-pass conduit 22'. This tubular plug has a closed end 24 protruding a substantial distance inside the body. This shear plug, as will be described in greater detail hereinafter, provides a means for equalizing the pressure inside the tube with the pressure outside the tube so that at the proper time the tube will contract to is normal or unstressed diameter and can be removed from the inside of the liner.

A combination standing and relief valve unit 25 is located at the lower end of the body 14. A standing valve seat as is threaded into the lower end of lower head 19. A tubular standing valve member 27 or tubing loading valve, comprising a part of the combination valve unit 25, in cooperation with this seat, permits the well fluids to enter the body 14 through the annular opening 28 as the mandrel is lowered into the well thereby filling the tubing with well liquids and equalizing the pressure in the mandrel with the external or well pressure. The lower end of the tubular standing valve member 27 is threaded into a movable relief valve cage 29. A ball valve'member 31 together with the lower end of the tubular valve member form a relief Valve. This ball valve member is seated in and held against the lower end of the tubular standing valve member 27 by spring 32. This ball valve member prevents well fluids from entering the lower end of the tubular standing valve member 27 but permits fluid to be released from inside the body when the difierential pressure across the relief valve is greater than the pressure at which this relief valve is set to open by the adjustment of spring tension adjusting screw 33. The adjusting screw is set at the surface to maintain sufficient differential pressure, typically -500 p.s.i. to inflate the rubber tube but to open before the differential pressure is great enough to rupand at the lower end to a'lower tubing string extension 37. A centralizer 38 may be mounted on the lower tubing string extension near the mandrel, on the tubing string above the mandrel, or centralizers may be placed both above and below the mandrel to protect the sleeve 13 from rubbing against the casing or the well wall as the sleeve and mandrel are lowered into the well. In some cases for the protection of the sleeve as it is run in the well, the lower centralizer may take the form of a solid gauge or a junk pusher larger than the assembled mandrel and sleeve.

In operation, the mandrel is assembled preferably in substantially the form described above. With the mandrel assembled at the surface, the sleeve 13 which will eventually form the well liner is made'up on the expandable tube 12. in substantially the following manner. The tube is first treated on the external surface with a parting compound to prevent the base resins from adhering to the tube surface. A heavy coating of wax such as a high- I softening-point carnauba Wax is first applied to the complete surface to be covered by the sleeve, allowed to harden, and then buffed smooth. Various silicone moldreleasing agents may additionally or alternatively be applied to the surface of the tube so that the cured resin will not adhere and the setting tool may be released from the liner and withdrawn from the well. A first layer of natural or synthetic fabric 39, preferably a piece of relatively coarse woven nylon or glass cloth such as Woven roving as long as the desired liner and as wide as the periphery of the well, is first impregnated with a resin,

. desirably a thermosetting resin, and then wrapped around the expansible tube. It may be wound around the tube spirally, i.e., with the edges overlapping, or it may be formed into a tube with a diameter equal to the casing or well diameter and folded or pleated around the tube with the pleats or corrugations running longitudinally of the tube. In some cases, it is desirable in addition to or in lieu of impregnating this fabriowith the thermosetting resin to brush, trowel, or butter a viscous resin, containing suflicient finely divided fillers such as fullers cart to make it of trowel consistency anda small amount (2-5 of a thickening or thixotroping agent such as a porous silica aerogel, on the fabric either before or after the fabric is placed on the expansible tube. This additional resin is desirably more viscous than the'resin with which the cloth is initially impregnated. The resin may be made viscous by the use of fillers such as silica flour as is well known in this art. In some cases, a second and even a third layer of this impregnated and/ or coated fabric is placed on the expansible tube in the same manner. The number of layers depends generally upon the thickness and strength of the liner desired, upon the conditions of the casing surface or well wall, and the amount of resin which is to be used. The greater the number of layers the more resin that can be applied and the stronger the liner. The number of layers is, however, limited in some cases by the permissible thickness of the liner. Each of these laminae may be held in place by lightly tacking the lapped ends or by a binding which is wrapped around the tube and the fabric. After the resin-saturated fabric 39 has thus been placed on the tube, it is covered and surrounded by a more rigid but permeable Woven fabric or screen 41 such as a coarse woven glass or metal screen like hardware cloth. Four to 50 mesh, typically about 20 mesh, vhardware or glass cloth is preferred. Owens-Coming Fiberglas Corporations square-woven fabric No. 162 is an example of a preferred glass fabric.

' Like the inner layers of plastic impregnated fabric, this outer screen is usually first saturated with the resin and then wrapped around the mandrel and the inner layer or layers of fabric thereon. It is also lightly tacked to hold it in position. This screen, also like the fabric underneath,

is desirably as long as the ultimate liner and is as wide as the circumference of the pipe to be patched. It may-be wrapped around the tube and underlying fabric spirally, i.e., with the edges overlapping, or it may be formed into a tube with a diameter equal to the casing or well diameter and folded or pleated around the tube with the pleats or corrugations running longitudinally of the'tube as shown in FIGURE 2. In some cases, the screen may be wide enough to provide more than one thickness when expanded and thus increase the strength of the liner. This screen serves a number of functions including holding the resin-impregnated fabric in place and protecting it from injury by contact with the well Wall as the sleeve is loweredinto the well. dinally permeable member around the fabric as the sleeve and liner are being expanded out into contact with the the pores of a formation or into holes behind the casing.

One particular advantage of the permeable sleeve and especially the outer lamina or screen is that the surplus resin is squeezed through one or more holes 43 or perforations in a casing 44 and forms on the outside of the casing buttons 45 which appear when set to plug the holes so that any reasonable amount of pressure can be:

applied externally and the casing liner will not leak or collapse.

Any resin which will cure or set hard, either naturally or artificially, in the well may be employed. Typically, these resins are thermosetting resins, i.e., resins which are capable of undergoing a permanent physical change under the influence of well temperature or an artificially induced higher temperature. examples. Other suitable resins include urea, resorcinol, and phenol formaldehydes, and the like. epoxy resin manufactured by Shell Chemical Compan' is an example of a preferred epoxy resin. As is well known in this art, these resins may be combined and various catalysts or curing agents employed in various concentrations so that the setting or curing time or pot life for various well depths or various temperatures may be controlled. Versamid resin 140, a polyamide manufactured by General Mills, 1110., is an example of a'pre ferred catalyst which, in the ratio of about 30 parts by volume to 70 parts of the Epon 828 epoxy resin, has a,

Such V pot life at room temperature of about 33% hours. resins when set, i.e., when they are cured sufficiently to be self-supporting and relatively rigid, are referred to herein as plastics.

After the sleeve or patch has thus been made up on the expansible tube and mandrel and the shear plug 23 has been installed and after the relief valve opening pressure has been set as previously described, the mandrel is ready to be lowered into the well. In most cases, however, before the apparatus is lowered into the well, it is desirable to locate accurately or otherwise know the elevation of a hole in the casing, of the casing perforations, or of a lost circulation zone to be sealed so that the liner can be placed at the proper elevation. Once the proper elevation is determined, it is also sometimes desirable to clean the surface where the liner is to be placed as by the use of chemicals or by abrasive means such as asteel brush, or both. The mandrel and sleeve are then lowered into position either on a wire line'or a tubing string. As the mandrel is lowered into the liquids in the well, the standing valve member 27 is raised to permit the well fluids Additionally, it provides a longitu:

Polyester or epoxy resins are I Epon 828, an

to enter the mandrel and the tubing string and thus substantially equalize the pressures inside and outside the tube and prevent it from being being collapsed. When the mandrel has been lowered to the proper depth so that the sleeve is located at a position opposite the zone to be lined, fluid is injected into the tubing string and suflicient pressure applied to expand the tube 12, break the fiber binding or tacking, and expand the sleeve 13 out against the surface of the casing or the well wall. Typically, suflicient pressure is applied to this fluid to produce a bearing pressure of 50400 or more pounds per square inch between the tube and the wall and to thereby squeeze the unset plastic or resin within the fibers into any voids or holes 43 in the well wall or in casing 44. The amount of pressure applied at the surface will, of course, depend upon the pop-off pressure of the relief valve, the static liquid level within the well, the density of the fluid in the tubing, the depth of the sleeve in the well, etc.

After fluid is injected into the mandrel to expand the tube and the laminated sleeve out against the wall of the casing or the well, pressure is maintained on the mandrel for several hours, typically from about to about 24 hours, or more, while the resin is cured or set and produces a hard immobile liner. During the time that the tube is thus expanded the liquid level in the well may tend to vary, especially in wells which are not initially at static equilibrium. During this time the pressures above and below the mandrel are equalized by fluid flow through bypass conduit 22 so that the well fluids will not unseat the expanded tube and flush away the unset resin. Where heat is desired to accelerate curing of the resin, 21 heat source may be lowered through the tubing string to heat the mandrel and adjacent areas.

After the resin has cured sufllciently to produce a selfsupporting strong liner, typically from several hours to a day or more, the setting tool is released by deflating the expanded tube. This may be accomplished by any of a number of means such as by injecting gas into the tubing string to displace liquid through the relief valve and then releasing the pressure on the tubing string at the surface so that the internal and external pressure on the expansible tube is balanced or otherwise suficiently equalized through the standing valve to collapse the rubber tube. In the preferred embodiment, the pressure Within the mandrel may be equalized with the external pressure by dropping a go-devil down the tubing. When it strikes the shear plug 23, the plug is broken and a port 42 through the wall of the upper head 18 is opened to permit liquid within the mandrel to flow to the annular space outside the tubing and equal ze the pressures inside and outside th resilient tube so that the tube 12 is contracted by its own resiliency.

With the expansible tube contracted away from the set liner, the tubing string and mandrel are pulled from the well. As they are removed from the well, the liquid within the tubing string discharges through the open port 42 maintaining only a small difierential pressure between the inside and outside of the mandrel. The resilient tube can, therefore, normally be withdrawn from the well without dilficulty and reused as many times as desired.

The thickness of the plastic liner left in the well depends generally upon the number of fabric and screen laminae used in the sleeve. It may vary from about A inch to about /2 inch or more but the liner is typically about /tinch thick. The liner thus leaves suflicient space to permit the mandrel with another sleeve mounted thereon to be run through the well and the liner to a greater depth so that deeper holes or perforations can subsequently be plugged.

From the foregoing, it can be seen that various modifications of the apparatus and procedure can be made without departing from the spirit of this invention. For example, whereas in the preferred embodiment an apparatus and procedure for placing a plastic patch in a Well have been particularly described, I have found that generally the same procedure can be employed not only to place a strong plastic patch over a hole or opening in any container, pressure vessel, or the like, but to place a liner in a vessel regardless of whether there is or is not a hole in the wall of the vessel. And whereas in the above description reference has been made to running the mandrel on a tubing string and expanding it by injecdng a fluid into the tube through the tubing string, the mandrel can be run on a wire line and in such instance the tube can be expanded either mechanically as by manipulation of the wire line or by an electric motor, or pneumatically as by the use or" gas generating chemicals, or the like. This invention should, therefore, be construed not to be limited by the description which has been given by way of example. It should instead be construed to be limited only by the scope of appended claims.

I claim:

1. An apparatus for placing a plastic liner in a well which includes a tubular body, means to attach said body to a runn ng string so that the inside of said body will be in direct fluid communication with said running string, a resilient tube surrounding said body, a thermosetting resin-impregnated expansible sleeve of laminated fiber surrounding said tube, means to hermetically seal the ends of said tube to said body, a first fluid passage from the inside of said body to the inside of said tube, a second fluid passage from the inside of said body to the well bore, a relief valve in said second fluid passage to limit the differential pressure between the inside of said body and the outside of said body, and a standing valve in said second fluid passage to permit well fluids to enter said body when the pressure in said well is greater than the fluid pressure within said body.

2. A mandrel for setting a plastic liner in a well including a tubular body, means to connect the upper end of said tubular body to a tubing string so that the inside of said body will be in direct fluid communication with said tubing string, at least one perforation in the wall of said tubular body, a resilient tube surrounding said body and said perforation, means to seal the upper end of said resilient tube to said tubular body above said perforation, means to seal the lower end of said resilient tube to said tubular body below said perforation, a fluid bypass in both directions around said tube which includes an axial conduit through said body, the upper end of said conduit extending through the wall of said tubular body above said resilient tube and the lower end of said conduit extending through the wall of said tubular body below said resilient tube so that the ends of said conduit are in fluid communication with the fluids outside said tubular body above and below said resilient tube, a shear plug in the Wall of said tubular body above said conduit initially closed but adapted to be broken and to then establish fluid communication between the inside and the outside of said tubular body, a fluid inlet at the lower end of said body, a pressure relief valve in said fluid inlet adapted to prevent fluids outside said tubular body from flowing into said tubular body but to permit fluids within said tubular body to be exhausted therefrom under a predetermined differential pressure, and a standing valve in said fluid inlet adapted to permit fluids outside said tubular body to flow into said tubular body and to prevent fluids within said tubular body from flowing out of said tubular body.

3. A mandrel according to claim 2 including a resinimpregnated expansible sleeve of laminated fiber mounted on said resilient tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,709,940 Johnston Apr. 23, 1929 2,231,282 Norris Feb. 11, 1941 2,287,076 Zachry June 23, 1942 2,441,894 Mennecier May 18, 1948 2,742,968 Hildebrandt Apr. 24, 1956 2,804,148 Schremp et a1 Aug. 27, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noo 3,134,442 May 26 1964 Earl R. Jennings It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Patent should read as corrected below.

Column 2 line 43 for "is" read its line 64,, for "fluid" read fluids column 4, line 55 for SS/ read 33/ column 6, line ll after "or the likeo" insert Examples of this type of equipment are illustrated in U0 S Patent 2 7813354 Boer et alo; U6 S, Patent 2,842,212 Lebourg; and U. 50 Patent 2,843,052 Andrus,

Signed and sealed this 24th day of November 1964,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attest'mg Officer Commissioner of Patents 

1. AN APPARATUS FOR PLACING A PLASTIC LINER IN A WELL WHICH INCLUDES A TUBULAR BODY, MEANS TO ATTACH SAID BODY TO A RUNNING STRING SO THAT THJE INSIDE OF SAID BODY WILL BE IN DIRECT FLUID COMMUNICATION WITH SAID RUNNING STRING, A RESILIENT TUBE SURROUNDING SAID BODY, A THERMOSETTING RESIN-IMPREGNATED EXPANSIBLE SLEEVE OF LAMINATED FIBER SURROUNDING SAID TUBE, MEANS TO HERMETICALLY SEAL THE ENDS OF SAID TUBE TO SAID BODY, A FIRST FLUID PASSAGE FROM THE INSIDE OF SAID BODY TO THE EINSIDE OF SAID TUBE, A SECOND FLUID PASSAGE FROM THE INSIDE OF SAID BODY TO THE WELL BORE, A RELLIEF VALVE IN SAID SECOND FLUID PASSAGE TO LIMIT THE DIFFERENTIAL PRESSURE BETWEEN THE INSIDE OF SAID BODY AND THE OUTSIDE OF SAID BODY, AND A STANDING VALVE IN SAID SECOND FLUID PASSAGE TO PERMIT WELL FLUIDS TO ENTER SAID BODY WHEN THE PRESSURE IN SAID WELL IS GREATER THAN THE FLUID PRESSURE WITHIN SAID BODY. 